KR20200010558A - Adjustable Stacked Phase Mode Feeding for 2D Steering of Antenna Arrays - Google Patents

Abstract

A power supply network, a steering apparatus and system for a steerable antenna array are described. The feed network includes a first and a second transverse electromagnetic (TEM) waveguide and first and second variable phase shifters located in separate TEM waveguides. The variable phase shifter results in an additional progressive electrical phase shift in the radiaSpeting element of the individual ring, from 0 to a controllable integer multiple of 2π radians, which is directly proportional to the angular position of the radiating element in the ring. The feed network includes first and second phase mode feed probes connected to separate radiated TEM waveguides, which provide separate phase mode feed ports. When the feed network is connected to the antenna array, two successive orders of phase mode are provided to the phase mode feed port. The order of the phase mode can be selected using a phase shift control signal that controls the integer multiple of the variable phase shifter.

Description

Adjustable Stacked Phase Mode Feeding for 2D Steering of Antenna Arrays

This application claims priority to US patent application Ser. No. 15 / 624,262, filed June 15, 2017, entitled “ADJUSTABLE STACKED PHASE-MODE FEED FOR 2D STEERING OF ANTENNA ARRAYS, the contents of which are incorporated herein by reference. .

The present disclosure relates to beam steering of an antenna array. In particular, the present disclosure relates to stacked phase mode feed networks for antenna arrays.

An antenna array is a set of individual radiating elements that are connected together to operate as a single antenna, with a main beam or lobe. In the past, an antenna array could be said to be a single antenna. Beam steering is the angular positioning of the main beam which controls at least one of the amplitude and phase of the individual radiating element. Beam steering allows the antenna array to transmit in a preferential direction, ie in the direction of the main beam, or to provide increased reception sensitivity to signals received from the direction of the main beam. Different phase modes of the antenna array can be combined to obtain the desired radiation pattern for the main beam.

The circuit for beam steering may include at least one of a separate phase shifter and a separate delay unit for each individual radiating element constituting the antenna array. As the target frequency range of the antenna increases, the ideal space of the radiating element in the array decreases. Unlike antenna structures, beam steering circuits and feed networks are generally not scaled to wavelengths, so reduced spacing between radiating elements can increase the complexity of implementing beam steering circuits and feed networks used to connect radiating elements. have.

In order to achieve a main beam with a larger slope from the Z axis (ie, larger radiated steering range, or polar angle), it may be necessary to combine the higher order phase modes of the antenna array.

In various examples, a sparse phase mode feed network is described. The feed network allows any number of radiating elements in the antenna array to be fed by a smaller number of phase mode feed probes. In the example disclosed herein, the feed network includes two feed ports and no Butler matrix to feed any number of radiating elements. Two waveguides are stacked, each providing one of the two ring concentric antenna arrays. The disclosed configuration allows the formation of two consecutive orders of phase mode, on the order of phase modes which are adjustable by control signals.

In some examples, the present disclosure discloses a feed network for a steerable antenna array. The feed network includes a waveguide assembly comprising a first radiant transverse electromagnetic (TEM) waveguide and a second radiated TEM waveguide and first and second variable phase shifters. The first radiating TEM waveguide comprises a plurality of first radiating element probes for connecting to radiating elements of the first ring of the antenna array, and the second radiating TEM waveguide is arranged for connecting to radiating elements of the second ring of the antenna array. Second radiating element probes. The first variable phase shifter is located in the first radiating TEM waveguide. The first variable phase shifter is configured to cause an additional gradual electrical phase shift in the radiating element of the first ring, from 0 to an integer multiple of 2π radians, which is directly proportional to the angular position of the radiating element in the first ring. Controllable. The second variable phase shifter is located in the second radiating TEM waveguide. The second variable phase shifter is configured to cause an additional gradual electrical phase shift in the radiating element of the second ring, from 0 to an integer multiple of 2 pi radians, which is directly proportional to the angular position of the radiating element in the second ring. Controllable. The feed network also includes first and second phase mode feed probes individually connected to the first and second radiating TEM waveguides. Phase mode feed probes provide separate phase mode feed ports. When the feed network is connected to the antenna array, two successive orders of phase mode are provided to the phase mode feed port, the order of the phase modes being at least one phase shift that controls an integer multiple of the first and second variable phase shifters. Selectable according to the control signal.

In any of the above embodiments / sides, the waveguide assembly may consist of a concentric antenna array. The first radiating TEM waveguide may be configured to be connected to an inner concentric ring of the antenna array, and the second radiating TEM waveguide may be configured to be connected to an outer concentric ring of the antenna array. The first and second radiating TEM waveguides may be stacked concentrically with each other.

In any of the above embodiments / sides, a lower order of the continuous order phase mode may be obtained from the first radiating TEM waveguide, and a higher order of the continuous order phase mode may be obtained from the second radiation. Can be obtained from a TEM waveguide.

In any of the above embodiments / sides, a higher order of the continuous order phase mode may be obtained from the first radiating TEM waveguide, and a lower order of the continuous order phase mode may be obtained from the second radiation. Can be obtained from a TEM waveguide.

In any of the above embodiments / sides, the waveguide assembly may consist of a polygonal antenna array.

In any of the above embodiments / sides, the first and second phase mode feed probes may be arranged coaxially.

In any of the above embodiments / sides, the first and second variable phase shifters may be liquid crystal analog phase shifters.

In any of the above embodiments / sides, separate first and second phase shift control signals can be used to individually control integer multiples of the first and second variable phase shifters. The first variable phase shifter may be controlled to cause a phase shift of the radiating element of the first ring from 0 to K2π radians. The second variable phase shifter may be controlled to cause a phase shift of the radiating element of the second ring from 0 to (K + 1) 2π radians, where K is an integer. The phase mode provided to the phase mode feed port may be a Kth and K + 1th order phase modes.

In any of the above embodiments / sides, the first radiating TEM waveguide may comprise a fixed spiral phase shifter. The fixed spiral phase shifter may be configured to cause an additional gradual electrical phase shift in the first ring of the antenna array from 0 to 2π radians. The first and second variable phase shifters may be controlled by a common phase shift control signal.

In any of the above embodiments / sides, the waveguide assembly may be comprised of an antenna array having circular polarization radiating elements. The first and second variable phase shifters may be controlled by a common phase shift control signal.

In some aspects, the present disclosure describes an apparatus for beam steering a steerable antenna array. The apparatus may include any of the power supply networks of the above embodiments; And a beam steering circuit. The beam steering circuit is connected to the phase mode feed port of the feed network. The beam steering circuit is configured to combine the two consecutive order phase modes to produce a main beam of the steerable antenna array. The beam steering circuit controls the polar and azimuth angles of the main beam to direct the main beam in a selected direction.

In any of the above embodiments / sides, the beam steering circuit includes a monitoring and control subcircuit configured to monitor the signal strength of at least one of the phase modes and provide feedback for the phase shift control signal. Can be.

In some aspects, the present disclosure describes a steerable antenna array system. The system includes a plurality of radiating elements arranged in a planar antenna array. The system also includes any feed network of any of the above embodiments and any beam steering circuit of any of the above embodiments.

In any of the above embodiments / sides, the planar antenna array is a circular antenna array and the radiating elements are arranged in concentric rings.

In any of the above embodiments / sides, the planar antenna array is a polygonal antenna array and the radiating elements are arranged in concentric polygons.

Reference will be made, by way of example, to the accompanying drawings that illustrate exemplary embodiments of the present application.
1 is a schematic diagram illustrating an exemplary system for beam steering of a planar circular antenna array.
FIG. 2 schematically illustrates the coupling of a variable phase shifter into one waveguide in the waveguide assembly of the feed network shown in FIG. 1.
3 is a schematic diagram illustrating an exemplary liquid crystal analog implementation of a variable phase shifter.
4 is a schematic diagram illustrating a stacked waveguide assembly showing the coupling of a variable phase shifter to each waveguide.
5 is a schematic diagram illustrating a stacked waveguide assembly showing the combination of a variable phase shifter and a fixed phase shifter with a waveguide.
6 is a schematic diagram illustrating the orientation of a circularly polarized light emitting element to achieve a first order phase mode increase.
7 is a schematic diagram of an exemplary beam steering circuit suitable for use in the system of FIG. 1.
8 illustrates an exemplary hybrid splitter / combiner suitable for use in the beam steering circuit of FIG. 7.
9 shows a simulation of the radiation pattern of an exemplary main beam, in an exemplary configuration of a stacked waveguide assembly.
10 shows a simulation of the radiation pattern of an exemplary main beam, in another exemplary configuration of a stacked waveguide assembly.
Similar reference numerals may have been used in other drawings to indicate similar components.

The present disclosure discloses a sparse phase mode feed network that does not require an entire N-port network to feed N radiating elements in an antenna array. In the example described below, two feed probes are used to feed two stacked waveguides. The phase mode at the two phase mode ports is two consecutive order phase modes (generally referred to as P _K and P _{K + 1} ), which can be selected using a control signal to control K. The example configuration disclosed herein may enable simple planar configuration without the use of a Butler matrix. Since a butler matrix is not required, space savings and reduction of feed loss can be achieved. The feed network disclosed may interfere with any suitable beam steering circuit, such as any beam steering circuit designed for a circular antenna array.

The example described below may be suitable for use with a planar circular antenna array having two concentric ring radiating elements. Examples of antenna arrays with concentric ring radiating elements are described in Tiezhu Yuan, Hongqiang Wang, Yuliang Qin, and Yongqiang Cheng, “Electromagnetic Vortex Imaging Using Uniform Concentric Circular Arrays”, IEEE Antennas and Wireless Propagation Letters, Vol. 15, pp. 1024-1027, 2016, the entirety of which is incorporated herein by reference.

The spatial combination of fields produced by the concentric radiating elements, fed by two consecutive phase modes, produces a 2D steerable beam of desired slope from the Z axis. A variable ratio combiner (VRC) can also be implemented in the beam steering circuit, as further described below.

1 schematically illustrates components of an example system for beam steering of a steerable antenna array. System 100 can be used for both transmission and reception. System 100 includes a circular antenna array (not shown) and a feed network 102. Other antenna array arrangements may be suitable, but in the example described herein the antenna array has a set of N radiating elements (not shown) arranged in a planar circular arrangement of two concentric rings. In general, if the radiating elements are arranged to generate a phase mode (eg, the radiating elements are arranged concentrically along the circumference of the polygon), the antenna array may be any arrangement of radiating elements (eg, circular or polygonal). In the configuration). The individual radiating elements are arranged at spatial intervals of approximately half of the wavelength λ for which the antenna array is designed to operate. Each individual radiating element is connected to a separate radiating element probe 104 of the radiating waveguide transition assembly 130. Each radiating element probe 104 provides a transmit or receive signal with an individual radiating element.

In the example shown, waveguide transition assembly 130 includes two stacked radiant transverse electromagnetic (TEM) waveguides 106a, with radiating element probes 104 arranged in a circular pattern at each radiating TEM waveguide 106. 106b) (generally referred to as radiating TEM waveguide 106), which corresponds to the concentric arrangement of radiating elements of the antenna array. The configuration of the radiating TEM waveguide 106 is described in 13 / 870,309 filed April 25, 2013; 14 / 295,235, filed June 3, 2014; 14 / 948,879, filed November 23, 2015; It may be similar to that described in US Patent Application No. 15 / 295,366, filed Oct. 17, 2016, all of which is incorporated herein by reference in its entirety with the appropriate modifications described herein. While the TEM waveguide 106 is stacked on each other, it should be noted that the radiating element probe 104 may be connected to radiating elements in the same or different planes. In this example, the TEM waveguide 106 is stacked with the top radiating TEM waveguide 106a smaller than the bottom radiating TEM waveguide 106b. In another example, the upper radiating TEM waveguide 106a can be larger than the lower radiating TEM waveguide 106b. In general, the upper and lower radiating TEM waveguides 106a and 106b may be referred to as first and second radiating TEM waveguides 106a and 106b. For ease of understanding, the following discussion will refer to upper and lower radiating TEM waveguides 106a and 106b, but it should be understood that the "top" and "bottom" are not intended to be limiting.

In this example, there are two feed probes 108a, 108b (generally referred to as feed probe 108) connected to the phase mode feed port 110 of the feed network 102. In particular, the butler matrix is not necessary, which can result in at least one of reduction in feed loss and space savings due to the butler matrix. Regardless of the number N of radiating elements, the number of phase mode feeding probes 108 is always two. In the example disclosed herein, the two feed probes 108 are provided in a coaxial configuration (also referred to as a triaxial configuration), but have a different arrangement of feed probes 108, eg, at least one or more conductor layers, Configurations with attached rings, caps, or other structures for at least one of impedance matching or tuning purposes may also be suitable.

In FIG. 1, the feed probe 108 is shown separately from the waveguide assembly 130 for clarity, but when implemented, the feed probe 108 is connected to the waveguide assembly 130. For example, as shown in FIG. 1, the inner feed probe 108a may be connected to the upper radiating TEM waveguide 106a and the outer probe 108b may be connected to the lower radiating TEM waveguide 106b. As shown in FIG. 1, the external probe 108b does not necessarily need to be provided by the outermost conductor of the coaxial feed probe 108. Similarly, internal probe 108a does not necessarily have to be provided by the innermost conductor of coaxial feed probe 108. In this particular example, the innermost coaxial cylinder of coaxial feed probe 108 protrudes into the top radiating TEM waveguide 106a (eg, about half or 1/8 wavelength into waveguide 106a), and the K-phase mode. It is connected with the signal (interface). The inner surface of the intermediate cylinder of the coaxial feed probe 108 provides a return path for the current of the Kth phase mode interface from the inner surface of the lower disk of the upper radiating TEM waveguide 106a. The outer surface of the intermediate cylinder of the coaxial feed probe 108 forms an interface to the K + 1 st phase mode signal at the lower radiating TEM waveguide 106b and is connected to the upper metal disk of the lower radiating TEM waveguide 106b. Similarly, the inner surface of the outermost cylinder of the coaxial feed probe 108 is connected to the lower disk of the bottom radiating TEM waveguide 106b and provides a return path for the current of the K + 1 st phase mode interface. All three coaxial conductors of the coaxial feed probe 108 are separated by a dielectric material, the bottom end of which may end in the same plane at or below the bottom conductor disk of the bottom radiating TEM waveguide 106b.

When the phase mode feed port 110 is connected to the phase mode feed probe 108, each phase mode feed port 110 is in accordance with an individual one of two consecutive orders of phase mode P _K and P _{K + 1} . May correspond to an antenna array that transmits or receives a signal, which is discussed further below. 1 shows an external feed probe 108b that provides a K + 1st phase mode when connected to the bottom radiated TEM waveguide 106b and an internal feed probe that provides a Kth phase mode when connected to the top radiated TEM waveguide 106a. 108a), but this can be reversed, as discussed further below.

The phase mode feed port 110 is connected to the beam steering circuit 120, which provides the main beam M steered at the main port 122. Examples of suitable beam laser circuits are described in the aforementioned US patent application.

The beam steering circuit 120 may combine the signals from the two phase mode feed ports 110 to obtain the desired main beam M directed in the desired direction. For example, two successive orders of phase mode of the antenna array can be combined to achieve the desired slope or polar angle of the main beam M. One difference in phase mode combination has been found to use a simple phase control to produce a main beam M that can be steered more easily in the circumferential direction. The beam steering circuit 120 may control the radiation (ie, polar angle) and circumference (ie, azimuth) directions of the main beam M to enable scanning of the antenna array in a desired direction. Phase shift control signal 155 is used to control the phase shift of the radiating element of the antenna array to produce the required phase mode. The phase shift control signal 155 is used to control the variable phase shifter (not shown in FIG. 1) in each radiating TEM waveguide 106 and is discussed further below. The variable phase shifter is shown helically in the various figures for illustrative purposes only. In addition, the variable phase shifter may be integrated into the waveguide assembly 130 and may not be visible from the outside. The phase shift control signal 155 may be output to the variable phase shifter from the beam steering circuit 120 or a separate circuit. The main beam M provided to the main port 122 of the beam steering circuit 120 is provided to the radio transceiver 140 for use in transmission / reception. Auxiliary outputs such as one or both of auxiliary signals A1 and A2 (see FIG. 7) may also be provided for purposes such as interference mitigation or direction finding.

An exemplary configuration of the radiating TEM waveguide 106 is now described. The upper and lower radiating TEM waveguides 106a and 106b may be similar in configuration, and the following description may similarly apply to both the upper and lower radiating TEM waveguides 106a and 106b. In one example, the upper and lower radiating TEM waveguides 106a and 106b differ in radius by half of the wavelength [lambda] in the dielectric material used in the construction. The λ / 2 difference in this radius between the upper and lower radiating TEM waveguides 106a and 106b has been found to achieve a main beam M with reduced side lobes. However, other dimensions may also be suitable.

The configuration example described herein may be suitable for use with a planar circular antenna array. In one example, each radiating TEM waveguide 106 comprises a substantially parallel conductive circular disk separated by about 1/4 wavelength [lambda] in the dielectric. The total thickness of the laminated waveguide assembly 130 is no more than about half the wavelength λ in air. The N radiating element probes 104 are about 1/4 wavelength lambda from the circumferential vertical conductive wall connecting the upper and lower circular disks in each radiating TEM waveguide 106. In the example shown, each radiating TEM waveguide 106 has the same number of probes 104 (corresponding to the configuration of radiating elements in the antenna array). In the lower radiating TEM waveguide 106b the probe 104 is disposed slightly wider than the half wavelength, and in the upper radiating TEM waveguide 106a the probe 104 is disposed slightly closer than the half wavelength; The average spacing of all probes 104 is approximately half wavelength. In another example, there may be different numbers of probes 104 for the two TEM waveguides 106, and the spacing of the probes 104 may be different. In this example, the radiation spacing between the probes 104 of the upper and lower TEM waveguide 106 is approximately half wavelength, but this may also vary. The N outer radiating element probes 104 have an outer conductor connected to the upper disk and an inner conductor that λ protrudes by about 1/8 wavelength into the space between the disk but does not contact the lower disk. The other inner conductors of the N radiating element probes 104 are connected to the radiating element via a matched impedance element feed plane or non-planar network. This planar structure can be easily integrated into antenna arrays and feed networks.

The dimension and characteristic of the above-mentioned structural example are demonstrated. In some examples λ = 1.876 mm. Examples of dielectrics used in coaxial probes and between discs have the following characteristics: ε _r = 7.1, DuPont 9K7 LTCC material, f = 60 GHz. In each TEM waveguide 106, the spacing between parallel metal disks = 0.53 mm (ie 0.2824 λ or approximately λ / 4). Probe height between the upper pair of parallel metal circular disks (which defines the top radiating TEM waveguide 106a) = 0.234 mm (ie, approximately lambda / 8). The innermost conductor of the coaxial probe has a diameter of 115 μm (about 0.0617λ). The central conductor has an outer diameter of 200 μm (or about λ / 10). The diameters of the inner and center conductors of the coaxial feed probe assembly 108 should have the same ratio as the center and outer conductors. Thus, the outermost conductor has a diameter of 348 μm, or about 0.16 to 0.1854 λ (not considering the thickness of the metal). In some examples, a cylindrical coaxial structure may be added to each coaxial conductor of the central feed probe 108 to optimize impedance matching for each radiating TEM waveguide 106. In this example, the characteristic impedance of the concentric inner and outer coaxial probes is 12.06 Ohms.

The radiating element probe 104 has an internal and external diameter of 115 μm (about 0.0617λ) and 200 μm (or about λ / 10), respectively, or another that facilitates matching of device impedance with that of the radiating TEM waveguide 106. May have dimensions. In the top radiating TEM waveguide 106a, the device probes 104 may be uniformly disposed around a circumference, i.e., a circle of radius about [lambda] / 4 smaller than necessary to space them apart at [lambda] / 2 intervals of 1.9196 mm. The vertical conductive wall connecting the upper and lower metal disks of the upper radiating TEM waveguide 106a may be 2.3886 mm in radius, which will be located λ / 4 further from the center than the device probe 104. The element probes 104 of the bottom radiating TEM waveguide 106b may be evenly spaced about a radius, or about 2.8576 mm, than the outer wall of the top waveguide 106a, and the bottom of the bottom radiating TEM waveguide 106b. The outer vertical wall connecting the upper and lower disks can have a radius of about [lambda] / 4 greater than that of the radius of the circle of its element probe 104, or about 3.3266 mm.

As also described in the other disclosures mentioned above, the radiating element itself can be embedded in the upper metal disk of the TEM waveguide 106, such as a cross slot, so that the element probe 104 can be omitted entirely.

2 schematically shows a variable rotating transition 150 integrated into one radiating TEM waveguide 106, which in this example is a bottom radiating TEM waveguide 106b. It is to be understood that other variable phase shifters 150 of similar or identical structure (eg, smaller or identical dimensions) may be similarly integrated into the top radiating TEM waveguide 106a. The variable phase shifter 150 is located in the radiating TEM waveguide 106b so that TEM waves propagating radially between the radiating radiating element probe 104 and the corresponding phase mode feed probe 108b are radiated TEM waveguide 106b. Experience a linearly varying electrical phase transition from 0 to K2π radians (corresponding to the radiation propagation distance of Kλ) in the azimuthal direction of internal propagation. Thus, the variable phase shifter 150 causes an additional phase shift in the radiating element, from a phase shift of zero to an integer multiple of 2π radians represented by K2π, where K is a selectable order corresponding to the order of the phase mode. Is an integer value, K is controlled by the phase shift control signal 155, and the phase shift proceeds for one complete physical angular cycle around the plane of the TEM waveguide 106b. Phase shifter 150 causes a phase shift in the radiating element that proceeds linearly from zero to K2π radians. That is, phase shifter 150 causes a phase shift in the radiating element that is directly proportional to the angular position of the radiating element in the circle. In general, for N uniformly spaced radiating elements, variable phase shifter 150 causes additional phase shifts in the mth radiating element equal to (mK2 [pi]) / N radians. If the radiating elements are arranged in a circular arrangement in a planar circular antenna array, the radiating elements in the first position have an additional phase shift of (K2π) / N radians, and the phase shift increases linearly in the circular direction (spiral in Fig. 2). As indicated by, the radiating element at the Nth position (adjacent to the first position) will have an additional phase shift of K2π radians. In some examples, phase shift control signal 155 may be provided as an adjustable voltage signal proportional to K. The phase shift control signal 155 may be provided by the beam steering circuit 120 or a separate circuit.

3 is a schematic diagram illustrating an exemplary liquid crystal analog implementation of variable phase shifter 150. The exemplary variable phase shifter 150 shown in FIG. 3 may be integrated into a dielectric between two disks of, for example, the radiating TEM waveguide 106. In this example, the variable phase shifter 150 has a circular configuration, causing a phase shift in the planar circular antenna array. Variable phase shifter 150 may be constructed similarly to the liquid crystal analog phase shifter described in US patent application Ser. No. 14 / 603,908, filed Jan. 23, 2015, the entire contents of which are incorporated herein by reference. In the example of FIG. 3, helical phase shifter 150 has toric shaped liquid crystal compartment 152. The liquid crystal compartment 152 may be similar to that described in “Liquid Crystal Enabled Substrate Integrated Waveguide Variable Phase Shifter for Millimeter-Wave Applications at 60 GHz and Beyond” Proceedings of IEEE International Microwave Symposium IMS, 2015 by Kuangda Wang and Ke Wu. The entirety of which is incorporated herein by reference.

The plurality of electrodes 158 are radially positioned around the liquid crystal compartment 152 and are connected by the same resistor 153. Variable phase shifter 150 has a first end 154 connected to ground and a second end 156 that receives a phase shift control signal 155 (which may be in the form of a control voltage). Variable phase shifter 150 produces an electric field that causes a gradual phase shift in the radiating element. Note that the number of electrodes 158 does not necessarily correspond to the number of radiating elements of the antenna array. However, it may be useful for the number of electrodes 158 to be at least equal to the number of radiating elements, ensuring that the phase shift generated in the radiating element proceeds linearly from 0 to K2π, which is dependent on the Kth order phase mode. Affect. Other configurations for the variable phase shifter 150 can be used. For example, if the antenna array has a non-circular arrangement of radiating elements, the variable phase shifter 150 may thus be non-circular in shape. Variable phase shifter 150 is located in the radiating TEM waveguide 106 to occupy an annular area between the phase mode feed probe 108 and the radiating element probe 104.

4 shows a stacked waveguide assembly 130 with each variable phase shifter 150 integrated into each radiating TEM waveguide 106. For clarity, FIG. 4 shows the top and bottom TEM waveguides 106a, 106b and feed probe 108 in an exploded view. In this example, the top radiating TEM waveguide 106a is provided with a first variable phase shifter 150a, which causes a linear phase shift from 0 to K2π around the radiating TEM waveguide 106a, resulting in a K-th order phase mode. Generate. The lower radiating TEM waveguide 106b is provided with a second variable phase shifter 150b, which causes a linear phase shift from zero to (K + 1) 2π around the radiating TEM waveguide 106a, resulting in a K + 1 order. Generate phase mode. As discussed further below, the order of phase mode is such that the phase mode of the K th order occurs from the lower emission TEM waveguide 106b and the phase mode of the K + 1 th order occurs from the upper emission TEM waveguide 106a. Can be reversed. The variable phase shifters 150a, 150b, for example, together with the appropriate circuits used to divide and modify the phase shift control signal 155 into separate signals proportional to K and K + 1, the common phase shift control. May be controlled by signal 155. Alternatively, two separate phase shift control signals 155 can be used, with the two phase shift control signals 155 individually proportional to K and K + 1.

Alternatively, the common phase shift control signal 155 proportional to K is used to directly control the two variable phase shifters 150a and 150b by adding a fixed spiral phase shifter, as schematically shown in the exploded view of FIG. Can be used. The configuration shown in FIG. 5 may be similar to the configuration of FIG. 4. However, the first and second variable phase shifters 150a and 150b are controlled by the common phase shift control signal 155 such that the first and second variable phase shifters 150a and 150b are linear from 0 to K2π. Make the phase shift. One of the radiating TEM waveguides 106 (in this example, the bottom radiating TEM waveguide 106b) causes a linear phase shift from 0 to 2 [pi] around the radiating TEM waveguide 106b, resulting in a total linearity around the radiating TEM waveguide 106b. The red phase shift is from 0 to (K + 1) 2π. Thus, while the configuration shown in FIG. 5 can achieve the same output at the phase mode feed port 110 as in the configuration of FIG. 4, the configuration shown in FIG. 5 is a single common phase shift control signal 155. It can be used to directly control both the first and second variable phase shifters 150a and 150b. It is to be understood that a fixed spiral phase shifter 160 may instead be provided to the top emitting TEM waveguide 106a to obtain a K + 1th order phase mode from the top emitting TEM waveguide 106a. Fixed spiral phase shifter 160 may be implemented in a manner similar to that shown in FIG. 3, but without variable control.

A fixed spiral phase shifter 160 may instead be provided to the top radiating TEM waveguide 106a so that it can be understood that the K + 1st order phase mode originates from the top radiating TEM waveguide 106a.

Alternatively, instead of using the fixed spiral phase shifter 160, when the radiating element is circularly polarized, the first phase mode increase can be achieved by proper orientation of the radiating element. 6 is a schematic diagram illustrating an example of an orientation of a circularly polarized radiating element in a circular antenna array. In this example, antenna array 170 includes radiating elements arranged in inner ring 172 and concentric outer ring 174. The radiating element of the inner ring 172 is coupled to the top radiating TEM waveguide 106a (not shown in FIG. 6), and the radiating element of the outer ring 174 is shown of the bottom radiating TEM waveguide 106b (not shown in FIG. 6). Not). As shown in FIG. 6, the polarization reference of the radiating element in the inner ring 172 is aligned in the same direction, and the polarization reference of the radiating element in the outer ring 174 is aligned in the radial direction. Thus, the primary phase mode increase is effective in the outer ring 174 because of the orientation of the circularly polarized radiating element in the outer ring 174, and a fixed spiral phase shifter 160 is not necessary. Using the arrangement shown in FIG. 6, a single common phase shift control signal 155 (proportional to K) is used to directly control both the first and second variable phase shifters 150a, 150b, and The two variable phase shifters 150a and 150b are essentially identical and can be controlled to provide the same phase shift, with no fixed spiral phase shifter 160 being required.

It should be understood that similar arrangements may be used where the polarization reference of the radiating element proceeds in the opposite direction, which may have an effect on reducing the first phase mode. In addition, the radial alignment of the polarization reference can be switched between the inner and outer rings 172, 174. That is, the polarization criteria of the radiating elements in the outer ring 174 may be aligned in the same direction, and the polarization criteria of the radiating elements in the inner ring 172 may be aligned radially.

Thus, Figures 4, 5 and 6 show an alternative approach for achieving two consecutive orders of phase mode at phase mode feed port 110. The approach implemented may be selected based on factors such as any or all of cost, size, and antenna characteristics. For example, the configuration shown in FIG. 6 may be limited only to antennas having circularly polarized radiating elements. The configuration shown in FIG. 4 may require the use of two separate phase shift control signals 155, but will provide greater flexibility in choosing which TEM waveguide 160 affects higher order phase modes. Can be. The resulting main beam steering effect is not dependent on which arrangement of FIG. 4, 5 or 6 is used. Whether a higher order phase mode is generated from the top emitting TEM waveguide 106a or the bottom emitting TEM waveguide 106b may be selected according to the desired beam shape, as discussed further below.

7 illustrates an example beam steering circuit 120 suitable for use with the example power feed network 102 as described herein. The beam steering circuit 120 controls the polar angle φ _S and the azimuth angle Θ _S of the main beam M. In FIG. 7, the feed network 102 for the circular antenna array is indicated by a star inside the concentric ring of the circular patch representing the radiating element of the antenna array. The spiral shape inside the star represents a variable phase shifter. In this example, two variable phase shifters are shown, but as discussed above with reference to FIGS. 4, 5, and 6, any of the above-described configurations may be combined with the beam beam steering circuit 120 of FIG. Can be used together.

In Fig. 7, the P _{K + 1} and P _K signals are connected to the beam steering circuit and combined at selected ratios of amplitude and phase, according to the circuit shown. An exemplary circuit includes two variable-ratio couplers (VRCs) 202 that set the polar angle φ _S by varying the electrical phase of the inner opposing phase shifter by ± Φ _S. The VRC 202 includes two hybrid splitters / combiners connected to each other via two phase shifters, each equal but providing opposite positive phase shifts.

8 shows an example of a hybrid splitter / combiner suitable for use with the VRC 202. The hybrid splitter / combiner can be 180 ° hybrid. The relationship between the ports of the hybrid 136 is as shown in FIG. 8.

Referring back to FIG. 7, the P _{K + 1} signal is connected to a phase shifter 204 that sets the azimuth angle Θ _S. The output of the beam steering circuit 120 is an auxiliary signal A ₁ together with the main beam M, which auxiliary signal A ₁ is for other purposes including, for example, at least one of interference mitigation, direction finding and feedback control. Can be used. In the example shown, signals M and A ₁ are formed from a phase mode signal as follows:

The example circuit of FIG. 7 provides both azimuth and radial steering of the main beam. The polar angle is controlled by controlling how the amplitudes of the phase mode signals are combined, and the azimuth angle is controlled by controlling how the phases of the phase mode signals are combined. The phase shift control signal 155 controls the amount of phase shift caused by the variable phase shifter of the feed network 102, which in turn is two successive orders (ie, K connected to the beam steering circuit 120). And K + 1) phase mode. Using the phase shift control signal 155, another value of K may be selected to access the higher order phase mode. By combining higher order phase modes, a larger axial tilt (ie a larger value of polar angle φ _S ) in the radial direction can be achieved in the main beam M. The azimuth steering direction θ _S may vary independently over the entire physical range of 2π (corresponding to the electrical phase shift range of 2π) by the phase shifter 204 for any radial slope direction, including different values of K. Can be. By repeatedly selecting different values of K (e.g., starting at 0 and increasing by 1 for each iteration), the value of K can be selected, and the beam steering circuit 120 can be selected to select the desired value of K. Monitor the signal from For example, the monitoring and control subcircuit 206 may be part of the beam steering circuit 120. The monitoring and control subcircuit 206 may include at least one of a processor and circuitry that monitors the signal strength of one or two phase modes and retrieves the value of K to achieve the maximum signal. This search for an appropriate value of K can be performed by monitoring the phase mode prior to coupling to the main beam M, for example using feedback as shown in FIG. 7. After the appropriate value of K has been selected, the phase shift control signal 155 may control the variable phase shifter of the feed network 102 to obtain the desired continuous order phase mode. Steering of the main beam M can be performed using suitable beam steering techniques.

9 shows a simulation of the radiation pattern of an exemplary main beam M in the exemplary configuration of waveguide assembly 130 and using the circuit of FIG. 7, with higher order phase mode (ie, P _{K + 1} ). Is from the bottom radiating TEM waveguide 106b, the lower order phase mode (i.e., P _K ) is from the top radiating TEM waveguide 106a, and the radius difference between the top and bottom radiating TEM waveguides 106a and 106b is The radiating element at lambda / 2 and fed by the TEM waveguide 166 is in the same plane. The simulation of FIG. 9 was performed for K = 0, 1, 2 and 3 (shown from left to right). 10 illustrates a simulation of the radiation pattern of an exemplary main beam, in another exemplary configuration of the stacked waveguide assembly 130 and using the circuit of FIG. 7. Similar to the simulation performed for FIG. 9, in the simulation performed for FIG. 10, the radius difference between the upper and lower radiating TEM waveguides 106a, 106b is λ / 2 and K = 0, 1, 2, and 3 (Shown from left to right). However, in the simulation of FIG. 10, the higher order phase mode (ie, P _{K + 1} ) is from the top radiating TEM waveguide 106a, and the lower order phase mode (ie, P _K ) is the lower emission TEM waveguide. Originating from 106b, all radiating elements of the concentric ring antenna array are in the same plane.

It can be seen that the radiation pattern of FIG. 9 has smaller side lobes than the radiation pattern of FIG. 10. Meanwhile, the radiation pattern of FIG. 10 may provide finer control of the radiation slope than the radiation pattern of FIG. 9. Thus, an appropriate configuration can be selected based on different applications.

The example disclosed herein may allow for greater tilt from the Z axis, compared to being possible with arrangements using only phase modes corresponding to K = 0, +1, -1, especially when limited 2D steering is desired Can be useful. In addition, the examples disclosed herein may enable a reduction in feed loss and a reduction in the number of phase shifters used. For example, because no Butler matrix is needed, the feed network can be simplified. Unlike many conventional approaches, the number of phase shifters that need to be controlled is a fixed small number, independent of the number of radiating elements of the circular antenna array.

The disclosed configuration can be implemented with feed and antenna arrays integrated into a planar structure. The overall planar configuration may facilitate integration with an axial radiating circular antenna array and a two axis phase mode capable beam steering subsystem.

The disclosed configuration allows any number of radiating elements to be fed using a fixed number of phase shifters independent of a number of elements, thereby enabling the realization of a low cost small antenna.

The example provided herein shows an implementation for a planar circular antenna array, but the teachings of the present disclosure may be suitable for a non-circular antenna array that includes a polygonal (eg, square) antenna array. The teachings of the present disclosure can be applied to partially filled antenna arrays as well as filled antenna arrays (eg, radiating slot arrays). In the case of a polygonal antenna array, the variable phase shifter is again located in the annular region between the central coaxial phase mode feed probe and the radiating element probe, and the phase shift proceeds in a linear progression in the circumferential direction around the polygon. Although the example described herein shows an implementation for an antenna array having two concentric rings of radiating elements, there may be a larger number of rings of concentric elements. For example, one or both of the radiating TEM waveguides may feed more than one ring of radiating elements.

The example disclosed herein may be useful for one or both of small cell, such as found in dense urban environments, microwave and millimeter wave (mmWave) antenna arrays in high capacity networks, for example. For example, electronic devices such as small cell backhaul, mmWave peer-to-peer wireless devices, or mobile phase communication (satcom) terminals may benefit from the disclosed examples.

The present disclosure may be embodied in other specific forms without departing from the subject matter of the claims. The described embodiments are to be considered in all respects only as illustrative and not restrictive. One or more selected features of the foregoing embodiments may be combined to create alternative examples that are not expressly described, and features suitable for such combinations are understood within the scope of the present disclosure.

All values and subranges within the disclosed ranges are also disclosed. In addition, while the systems, devices, and processes disclosed and illustrated herein may include a particular number of devices / components, the systems, devices, and assemblies may be modified to include more or fewer such devices / components. For example, although any device / component disclosed may be referred to in the singular, the embodiments disclosed herein may be modified to include a plurality of such devices / components. The subject matter described herein is intended to cover and encompass all suitable modifications of the technology.

Claims (15)

A feed network for a steerable antenna array,
A first radiating transverse electromagnetic (TEM) waveguide and a second radiating TEM waveguide, wherein the first radiating TEM waveguide comprises a plurality of first radiating element probes for connecting to radiating elements of a first ring of the antenna array; And the second radiating TEM waveguide comprises a plurality of second radiating element probes for connecting to radiating elements of a second ring of the antenna array;
A first variable phase shifter located in the first radiating TEM waveguide, wherein the first variable phase shifter is from 0 to an integer multiple of 2π radians, directly proportional to the angular position of the radiating element in the first ring Is configured to cause an additional gradual electrical phase shift in the radiating element of the ring, the integer multiple being controllable;
A second variable phase shifter located in said second radiating TEM waveguide, said second variable phase shifter from 0 to an integer multiple of 2 pi radians, directly proportional to the angular position of the radiating element in said second ring; Is configured to cause an additional gradual electrical phase shift in the radiating element of the ring, the integer multiple being controllable; And
First and second phase mode feed probes individually connected to the first and second radiating TEM waveguides, the phase mode feed probes providing separate phase mode feed ports;
Including a waveguide assembly comprising a,
When the feed network is connected to the antenna array, two successive orders of phase mode are provided to the phase mode feed port, the order of phase mode being at least to control an integer multiple of the first and second variable phase shifters. Selectable according to one phase shift control signal,
Feeding network. The method of claim 1,
The waveguide assembly consists of a concentric antenna array,
The first radiating TEM waveguide is configured to be connected to an inner concentric ring of the antenna array,
The second radiating TEM waveguide is configured to be connected to an outer concentric ring of the antenna array,
Wherein the first and second radiating TEM waveguides are stacked concentrically with each other,
Feeding network. The method of claim 2,
The lower order of the continuous order phase mode is obtained from the first radiating TEM waveguide,
The higher order of the continuous order phase mode is obtained from the second radiating TEM waveguide,
Feeding network. The method of claim 2,
A higher order of the continuous order phase mode is obtained from the first radiating TEM waveguide, and a lower order of the continuous order phase mode is obtained from the second radiating TEM waveguide,
Feeding network. The method according to any one of claims 1 to 4,
Wherein the waveguide assembly consists of a polygonal antenna array,
Feeding network. The method according to any one of claims 1 to 5,
Wherein the first and second phase mode feed probes are arranged coaxially,
Feeding network. The method according to any one of claims 1 to 6,
Wherein the first and second variable phase shifters are liquid crystal analog phase shifters,
Feeding network. The method according to any one of claims 1 to 7,
Separate first and second phase shift control signals are used to individually control integer multiples of the first and second variable phase shifters,
The first variable phase shifter is controlled to cause a phase shift of the radiating element of the first ring from 0 to K2π radians,
The second variable phase shifter is controlled to cause a phase shift of the radiating element of the second ring from 0 to (K + 1) 2π radians, where K is an integer and is provided to the phase mode feed port. Is the Kth and K + 1th order phase modes,
Feeding network. The method according to any one of claims 1 to 8,
Further comprising a fixed spiral phase shifter in the first radiating TEM waveguide,
The fixed spiral phase shifter is configured to cause an additional gradual electrical phase shift in the first ring of the antenna array from 0 to 2π radians,
Wherein the first and second variable phase shifters are controlled with a common phase shift control signal,
Feeding network. The method according to any one of claims 1 to 9,
The waveguide assembly consists of an antenna array having circularly polarized radiating elements,
Wherein the first and second variable phase shifters are controlled with a common phase shift control signal,
Feeding network. An apparatus for beam steering a steerable antenna array,
The power supply network of claim 1; And
A beam steering circuit connected to a phase mode feed port of the feed network
Including,
The beam steering circuit is configured to combine the two consecutive order phase modes to produce a main beam of the steerable antenna array,
The beam steering circuit controls the polar and azimuth angles of the main beam to direct the main beam in a selected direction,
Device. The method of claim 11,
The beam steering circuit,
A monitoring and control subcircuit configured to monitor signal strength of at least one of the phase modes and provide feedback for the phase shift control signal. A steerable antenna array system,
A plurality of radiating elements arranged in the planar antenna array;
The power supply network of claim 1; And
A beam steering circuit connected to a phase mode feed port of the feed network
Including,
The beam steering circuit is configured to combine the two consecutive order phase modes to produce a main beam of the steerable antenna array,
The beam steering circuit controls the polar and azimuth angles of the main beam to direct the main beam in a selected direction,
system. The method of claim 13,
The planar antenna array is a circular antenna array,
The radiating elements are arranged in concentric rings,
system. The method of claim 13,
The planar antenna array is a polygonal antenna array,
The radiating elements are arranged in concentric polygons,
system.

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